1. Field of the Invention
The present invention relates to a rotor blade flap driving apparatus for driving a flap provided to a trailing edge of each rotor blade of a helicopter or the like.
2. Description of the Related Art
In recent years, there have been increasing demands for commuter helicopters which take off and land on heliports in urban areas. To realize this, noise reduction is highly required. As an effective anti-noise measure, a method has been considered in which a flap is attached to each rotor blade of a helicopter and the flap is driven at a high speed of approximately 30 Hz to 50 Hz and precisely controlled to thereby improve the aerodynamic characteristics of the rotor blades.
As an actuator for use in a flap driving apparatus of such a rotor blade is employed a small-size and lightweight one because the actuator must be housed in the rotor blade. For example, a stack-type piezo-actuator in which thin plates of piezoceramic elements are stacked is used, however, in such a stack-type piezo-actuator, since the amount of displacement is small, it is required to magnify the displacement to drive the flap.
In a configuration in which the displacement of the actuator is magnified simply with a lever or the like, however, it is difficult to obtain a magnification factor large enough to make an angular displacement to drive the flap.